Atomizing nozzle and pouring cup assembly for the manufacture of metal powders



Jan. 17, 1961 R. L. PROBST ETAL ATOMIZING NOZZLE AND POURING CUPASSEMBLY FOR THE MANUFACTURE OF METAL POWDERS Filed March 23, 1959 4Will United States Patent Cfiice 2,968,062 Patented. Jan. :11, .1961

This invention relatesgeneral-ly to apparatus for making metal powdersand more; particularly toapouringcup and nozzle assembly which-iscapable-of producing dense metal particles'of very finesize. V

i The production of metal powders .which.=are made up of particles in adesired-range of sizes land whicharealso clean and of low oxidecontent'and-whichcan be produced from a widerangeof metal alloy.compositions has'been a desirable objective for some time. However,previously available equipment has not been capable of producingsatisfactory-powders of this type.

It is an object of this invention, t-herefore, to provide a pouring cupand atomizingnozzle assembly which is capable of manufacturingmetalpowders :from :any elemental metal or any known alloy compositionand having particles in the various size ranges desired which-have-a lowoxidecontent and meet thenecessary density-objectives.

A further object of this invention is-to provide an atomizing nozzle andpouring cup assembly whichis simple in construction, economical tomanufacture, and efiicient in operation I in producing clean highdensity metals powders.

Further objects, features and advantagesof this invention will becomeapparent from 'acon'sideration of the following description,--theappended' cla'ims arid the accompanying drawing inwhich:

Figure 1 is a vertical'sectional view'of the pouring cup and nozzleassembly of this invention; and

Figure 2 is "a horizontal sectional view of the, assembly of thisinvention, lookingsubStantially along the line 22 in Fig. 1.

The pouring cup and nozzle assembly of this invention, indicatedgenerally at 10, is illustrated in Fig. l as consisting of a cup member12 formed of a ceramic or refractory material which is capable of beingheated to the temperature of the molten metal which is to be atomizedand formed into a powder. The cup 12 is formed with an upwardly facingcavity 14 into which the metal to be atomized is poured and a dependingcylindrical stem portion 16 which has an axial passage 18 thatcommunicates at its upper end with the cavity 14 and terminates at itslower end in the center of the lower end surface 20 of the stem portion16. The cup 12 has an annular bottom surface 22 which surrounds the stemportion 16 and is fiat for seating the cup 12 on the top side of anozzle unit 24 which is of an annular shape and extends about the stemportion 16.

The nozzle unit 24 consists of a bottom plate section 26, an uppersection 28 which is secured by bolts 30 to the lower section 26, and anozzle insert 32 arranged in a coaxial relation with the stem portion16. The lower plate section 26 is circular and has a central opening 34defined by an edge surface 36 which is of a downward and axially inwardinclination. As a result, the opening 34 is of a progressively smallerdiameter in a downward direction.

The upper nozzle section 28 has an upper plate portion "2 38 provided.with-a depending annular outer or flange 40'which cooperates withtheplateportion 3 8, to

. form agdownwardly. facing cavity 142. The .plate portion 38 also hasa.central opening 44which ispositi'on edxin verticalalignmentwith theopening 34. A threaded inlet: opening .46 in1the wall 40 =of,'t he uppersection-28 is adapted to be'connected-to a;suitable supply. pipe for theatomizing medium such as -a fluid and/ongaswith which the cavity 42 isto-be supplied.

The nozzle insert 32 is generally tubular in shape and has its bottomendsurface 48- arranged: in a concentric parallel relation with-the surface36 on thelower plate section 26. In other words, the angular inclinationof the surface 48relativeto, a horizontal planecorresponds to theangularrinclinationof-the. surface 36. In the illustrated embodiment ofthe invention this inclination is about sixty degrees. .The outerdiameter of-the-nozzle insert 32 provides for a pressed fit of thenozzle -insert--32 in the opening 44 in the top section 38. The innersurface of the nozzle insert 32 is tapered so that the diameter thereofdecreases in :a downward direction to facilitate the nesting therein ofthe-stem portion '16 which is similarly tapered to provide for a tightfit of the stem portion 16 in the-insert 32. As showninFig. 1, the cupstem portion 16 has its inclined lower end surface 20 extended outwardlyso thatrit intersects the outer .generally'cylindrical surface 50 of thestem 16 so as to form a relatively sharp edge 52 at the lower endof thestemportion16. This edge 52 is located below the. lowerend of m mainsert 32 at least one-sixteenth ofnan inch so that-it is positioneddirectly in the path of the atomizing medium issuing from the nozzleunit.

In the use-of"the assembly lll,.a:suitable atomizing medium underpressure-is supplied to the cavity :42. :In one embodimentof theinvention, this medium isrnitrogen gas and thepressure of this gas:builds-upin-cavity .42

so that it issues from the downwardly and inwardlyinclined outletpassage 56 formedbetween theti nclined surfaces 36 and =48,as va streamtraveling at aihigh rate of .speed. The size ofthe.passage"52fis-maintained between 0.01 inch and 0.04 inch dependingupon the atomizing -medium'which issiipplied'to'the cavity 42. Thepassage sizeis readily 'adjusted'by rriovingl the nozzle insert 32toward "or away fromthe "bo't'tomplate section 26.

This stream of gas travels inwardly across the lower edge 52 of the cupstem portion 16 and creates a vacuum Within the frusto-conical space 60enclosed within the annular surface 20. This vacuum draws the moltenmetal in the cup 12 downwardly through the discharge passage 18 which isbetween one-sixteenths and three-eighths inch in diameter so as toprovide for a downwardly moving film of metal on the surface 20. Inaddition, this vacuum seats the tapered stem portion 16 tightly in thetapered nozzle insert 32.

The molten metal travels outwardly on the inclined surface 20 to theedge 52 where the atomizing medium issuing from the discharge passage 56intersects the stream of metal at substantially right angles. The forceof this moving stream atomizes the molten metal into small particles.

The size of these particles is dependent primarily upon the pressure inthe cavity 42; the higher the pressure, the smaller the particle size.For example, using a 316 stainless steel as the material to be atomized,when a pressure of four hundred pounds per square inch (400 p.s.i.) inthe chamber 42 is used, seventy-seven percent of the yield was of minusone hundred mesh size. When, in a subsequent test, the pressure wasdropped to one hundred pounds per square inch psi), only fortytwopercent of the yield was minus one hundred mesh size.

In practice, atomizing pressures have ranged between seventy pounds persquare inch (70 p.s.i.) and seven hundred pounds per square inch (700p.s.i.) in the successful production of powder. The edge 52 ismaintained in a sharp condition to prevent the metal from cooling andsolidifying thereon and the diameter of the opening 18 is maintainedbetween one-sixteenth and threeeighths of an inch. The thinner the filmof metal that is supplied to the edge 52, of course, the smaller theparticle size. For example, using 316 stainless steel as the material tobe atomized and using a pressure of one hundred pounds per square inch(100 p.s.i.) in the chamber 42, a forty-two percent minus one hundredmesh yield is obtained with a three-sixteenths of an inch diameteropening 18. This percentage drops to twenty-one percent when thediameter is increased to three-eighths of an inch.

Although the invention has been described with respect to a preferredembodiment thereof, it is to be understood that it is not to be solimited, since changes can be made therein which are within the scope ofthe invention as defined by the appended claims.

What is claimed is:

1. Apparatus for manufacturing metal powder comprising means forming adownwardly extending discharge passage for molten metal, said meanshaving an outer surface and an annular downwardly and outwardly inclinedlower end surface communicating at substantially the center of the upperend thereof with the discharge end of said passage and intersecting saidouter surface at the lower end thereof to thereby form an outer edge,and nozzle means arranged in a substantially concentric relation withsaid annular surface, said nozzle means having discharge passage meansarranged so that an annular downwardly inclined stream of gas from saidnozzle means is directed across said outer edge of said inclined surfacefor drawing molten metal out the lower end of said discharge passage sothat it flows downwardly on said end surface and said gas streamatomizes the molten metal flowing ofi said edge to thereby form metalparticles.

2. Apparatus for manufacturing metal powder comprising means having agenerally cylindrical downwardly extending portion provided with anaxial discharge passage for molten metal, said cylindrical portionterminating at its lower end in an annular surface which is inclineddownwardly and outwardly from the lower discharge end of said passageand intersects the cylindrical outer surface of said portion so as toform therewith a relatively sharp edge, and nozzle means extending aboutsaid cylindrical portion for directing a downwardly inclined stream ofgas across said sharp edge for drawing molten metal out the lower end ofsaid discharge passage so that it flows downwardly on said end surfaceand said gas stream atomizes the molten metal flowing off said edge tothereby form metal particles, said surface and said stream beingsubstantially at right angles relative to each other.

3. Apparatus for manufacturing metal powder comprising means having agenerally cylindrical downwardly extending portion provided with anaxial discharge passage for molten metal, said cylindrical portionterminating at its lower end in an annular surface which is inclineddownwardly and outwardly from the lower discharge end of said passageand intersects the cylindrical outer surface of said portion so as toform therewith a relatively sharp edge, and nozzle means extending aboutsaid cylindrical portion for directing a downwardly inclined stream ofgas across said sharp edge for drawing molten metal out the lower end ofsaid discharge passage so that it flows downwardly on said end surfaceand said gas stream atomizes the molten metal flowing off said edge tothereby form metal particles, said surface and said stream beingsubstantially at right angles relative to each other, said nozzle meansincluding a member positioned about said passage means and having anopening bounded by an annular surface which is inclined downwardlytoward the axis thereof, a tubular nozzle insert member positioned aboutand arranged in a tight fit relation with said cylindrical portion andhaving the lower end surface thereof positioned Within said opening andinclined downwardly in a parallel spaced relation with said annularsurface, said spaced surfaces forming an outlet passage for said nozzlemeans arranged so that said sharp edge is in the path of gas dischargedtherefrom.

References Cited in the file of this patent UNITED STATES PATENTS1,245,328 Freeman Nov. 6, 1917 2,636,219 Beamer et a1 Apr. 28, 19532,892,215 Naeser et al. June 30, 1959 FOREIGN PATENTS 693,943 GreatBritain July 8, 1953 712,699 Great Britain July 28, 1954

